Tectonic controls on residual oil saturation below the present-day fluid contact level in reservoirs of the Persian Gulf

Ebrahim Heydari Farsani*, J. E. Neilson, G. I. Alsop, Hossein Hamidi

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

The presence of residual oil below the present-day free water level (FWL) and oil water contact (OWC) is common in many oil fields in the Middle East, particularly those in the Persian Gulf. This residual oil is seen in both clastic and carbonate reservoirs prior to the start of production. The characterisation and modelling of these fields is difficult in practice. Also, these residual oils below the FWL and OWC could become classified as reserves if ways to produce them could be found. However, the first step is to better understand their origin. Therefore, the goal of this study was to investigate the role of geological events on the presence of the residual oil zone (ROZ) below the FWL and OWC.
It has been suggested that the presence of residual oil below the present day FWL and OWC is related to the geotectonic history of the region. From the middle Miocene, reverse faulting and overfolding propagated over the Zagros, leading to the amplification of folds and the migration of the Zagros orogeny towards its foreland basin (Persian Gulf). In response to this additional massive loading on the continental margin, the forebulge amplitude was increased, its location migrated towards the uplifted Zagros Mountains, and consequently the Persian Gulf became narrower. This exerted a north to north-east downward tilting of the entire basin, including all the structures and reservoirs previously filled by hydrocarbons. This basin tilting changed the equilibrium of the structures and their fluid contents, and resulted in the hydrocarbons and water attempting to find a new equilibrium. Under these conditions, the early migrated and accumulated oil was flushed out by water (imbibition), and a ROZ was left below the present day FWL and OWCs. The angle of regional basin tilt has been calculated to be 0.836° based on seismic sections.
Original languageEnglish
Article number104133
JournalJournal of Asian Earth Sciences
Early online date19 Nov 2019
DOIs
Publication statusE-pub ahead of print - 19 Nov 2019

Fingerprint

saturation
tectonics
fluid
oil
water level
water
gulf
basin
hydrocarbon
imbibition
foreland basin
tilt
orogeny
oil field
continental margin
amplification
faulting
Miocene
fold
carbonate

Keywords

  • Residual oil below fluid contact
  • Zagros collision
  • Persian Gulf
  • foreland basin
  • regional tilting

Cite this

@article{c82b3f22e6404d04b8881f7f2762ea18,
title = "Tectonic controls on residual oil saturation below the present-day fluid contact level in reservoirs of the Persian Gulf",
abstract = "The presence of residual oil below the present-day free water level (FWL) and oil water contact (OWC) is common in many oil fields in the Middle East, particularly those in the Persian Gulf. This residual oil is seen in both clastic and carbonate reservoirs prior to the start of production. The characterisation and modelling of these fields is difficult in practice. Also, these residual oils below the FWL and OWC could become classified as reserves if ways to produce them could be found. However, the first step is to better understand their origin. Therefore, the goal of this study was to investigate the role of geological events on the presence of the residual oil zone (ROZ) below the FWL and OWC.It has been suggested that the presence of residual oil below the present day FWL and OWC is related to the geotectonic history of the region. From the middle Miocene, reverse faulting and overfolding propagated over the Zagros, leading to the amplification of folds and the migration of the Zagros orogeny towards its foreland basin (Persian Gulf). In response to this additional massive loading on the continental margin, the forebulge amplitude was increased, its location migrated towards the uplifted Zagros Mountains, and consequently the Persian Gulf became narrower. This exerted a north to north-east downward tilting of the entire basin, including all the structures and reservoirs previously filled by hydrocarbons. This basin tilting changed the equilibrium of the structures and their fluid contents, and resulted in the hydrocarbons and water attempting to find a new equilibrium. Under these conditions, the early migrated and accumulated oil was flushed out by water (imbibition), and a ROZ was left below the present day FWL and OWCs. The angle of regional basin tilt has been calculated to be 0.836° based on seismic sections.",
keywords = "Residual oil below fluid contact, Zagros collision, Persian Gulf, foreland basin, regional tilting",
author = "{Heydari Farsani}, Ebrahim and Neilson, {J. E.} and Alsop, {G. I.} and Hossein Hamidi",
note = "Acknowledgments The authors would like to acknowledge, and gratefully appreciate the support of, the Aberdeen Formation Evaluation Society for their sponsorship, and Emerson (Paradigm) for providing the Geology software for the development of this study.",
year = "2019",
month = "11",
day = "19",
doi = "10.1016/j.jseaes.2019.104133",
language = "English",
journal = "Journal of Asian Earth Sciences",
issn = "1367-9120",
publisher = "Elsevier",

}

TY - JOUR

T1 - Tectonic controls on residual oil saturation below the present-day fluid contact level in reservoirs of the Persian Gulf

AU - Heydari Farsani, Ebrahim

AU - Neilson, J. E.

AU - Alsop, G. I.

AU - Hamidi, Hossein

N1 - Acknowledgments The authors would like to acknowledge, and gratefully appreciate the support of, the Aberdeen Formation Evaluation Society for their sponsorship, and Emerson (Paradigm) for providing the Geology software for the development of this study.

PY - 2019/11/19

Y1 - 2019/11/19

N2 - The presence of residual oil below the present-day free water level (FWL) and oil water contact (OWC) is common in many oil fields in the Middle East, particularly those in the Persian Gulf. This residual oil is seen in both clastic and carbonate reservoirs prior to the start of production. The characterisation and modelling of these fields is difficult in practice. Also, these residual oils below the FWL and OWC could become classified as reserves if ways to produce them could be found. However, the first step is to better understand their origin. Therefore, the goal of this study was to investigate the role of geological events on the presence of the residual oil zone (ROZ) below the FWL and OWC.It has been suggested that the presence of residual oil below the present day FWL and OWC is related to the geotectonic history of the region. From the middle Miocene, reverse faulting and overfolding propagated over the Zagros, leading to the amplification of folds and the migration of the Zagros orogeny towards its foreland basin (Persian Gulf). In response to this additional massive loading on the continental margin, the forebulge amplitude was increased, its location migrated towards the uplifted Zagros Mountains, and consequently the Persian Gulf became narrower. This exerted a north to north-east downward tilting of the entire basin, including all the structures and reservoirs previously filled by hydrocarbons. This basin tilting changed the equilibrium of the structures and their fluid contents, and resulted in the hydrocarbons and water attempting to find a new equilibrium. Under these conditions, the early migrated and accumulated oil was flushed out by water (imbibition), and a ROZ was left below the present day FWL and OWCs. The angle of regional basin tilt has been calculated to be 0.836° based on seismic sections.

AB - The presence of residual oil below the present-day free water level (FWL) and oil water contact (OWC) is common in many oil fields in the Middle East, particularly those in the Persian Gulf. This residual oil is seen in both clastic and carbonate reservoirs prior to the start of production. The characterisation and modelling of these fields is difficult in practice. Also, these residual oils below the FWL and OWC could become classified as reserves if ways to produce them could be found. However, the first step is to better understand their origin. Therefore, the goal of this study was to investigate the role of geological events on the presence of the residual oil zone (ROZ) below the FWL and OWC.It has been suggested that the presence of residual oil below the present day FWL and OWC is related to the geotectonic history of the region. From the middle Miocene, reverse faulting and overfolding propagated over the Zagros, leading to the amplification of folds and the migration of the Zagros orogeny towards its foreland basin (Persian Gulf). In response to this additional massive loading on the continental margin, the forebulge amplitude was increased, its location migrated towards the uplifted Zagros Mountains, and consequently the Persian Gulf became narrower. This exerted a north to north-east downward tilting of the entire basin, including all the structures and reservoirs previously filled by hydrocarbons. This basin tilting changed the equilibrium of the structures and their fluid contents, and resulted in the hydrocarbons and water attempting to find a new equilibrium. Under these conditions, the early migrated and accumulated oil was flushed out by water (imbibition), and a ROZ was left below the present day FWL and OWCs. The angle of regional basin tilt has been calculated to be 0.836° based on seismic sections.

KW - Residual oil below fluid contact

KW - Zagros collision

KW - Persian Gulf

KW - foreland basin

KW - regional tilting

U2 - 10.1016/j.jseaes.2019.104133

DO - 10.1016/j.jseaes.2019.104133

M3 - Article

JO - Journal of Asian Earth Sciences

JF - Journal of Asian Earth Sciences

SN - 1367-9120

M1 - 104133

ER -